Re: [PATCH v6 3/6] asm-generic: add generic seccomp.h for secure computing mode 1

Kees Cook
2014-08-21T17:51:54Z

On Thu, Aug 21, 2014 at 3:56 AM, AKASHI Takahiro
<takahiro.akashi@linaro.org> wrote:
> Those values (__NR_seccomp_*) are used solely in secure_computing()
> to identify mode 1 system calls. If compat system calls have different
> syscall numbers, asm/seccomp.h may override them.
>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

> ---
> include/asm-generic/seccomp.h | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
> create mode 100644 include/asm-generic/seccomp.h
>
> diff --git a/include/asm-generic/seccomp.h b/include/asm-generic/seccomp.h
> new file mode 100644
> index 0000000..5e97022
> --- /dev/null
> +++ b/include/asm-generic/seccomp.h
> @@ -0,0 +1,28 @@
> +/*
> + * include/asm-generic/seccomp.h
> + *
> + * Copyright (C) 2014 Linaro Limited
> + * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#ifndef _ASM_GENERIC_SECCOMP_H
> +#define _ASM_GENERIC_SECCOMP_H
> +
> +#include <asm-generic/unistd.h>

While this isn't a problem for ARM, this should be linux/unistd.h for
other architectures to get the right stuff.

> +
> +#if defined(CONFIG_COMPAT) && !defined(__NR_seccomp_read_32)
> +#define __NR_seccomp_read_32 __NR_read
> +#define __NR_seccomp_write_32 __NR_write
> +#define __NR_seccomp_exit_32 __NR_exit
> +#define __NR_seccomp_sigreturn_32 __NR_rt_sigreturn
> +#endif /* CONFIG_COMPAT && ! already defined */
> +
> +#define __NR_seccomp_read __NR_read
> +#define __NR_seccomp_write __NR_write
> +#define __NR_seccomp_exit __NR_exit
> +#define __NR_seccomp_sigreturn __NR_rt_sigreturn

Some architectures use __NR_sigreturn, so this will need to be
adjusted in the future into:

#ifdef __NR_seccomp_sigreturn
#define __NR_seccomp_sigreturn __NR_rt_sigreturn
#endif

After these changes, I was able to port x86 to using this
asm-generic/seccomp.h too.

-Kees

> +
> +#endif /* _ASM_GENERIC_SECCOMP_H */
> --
> 1.7.9.5
>

--
Kees Cook
Chrome OS Security